You Do Need power plug adapter while traveling from Madagascar to South Africa.

Here is Why You Need An Adapter

The outlet and plug type used in South Africa are C, M and N and in Madagascar are C and E. This is how they look like.

Madagascar

In Madagascar, outlets of type C and E are in use.

Type C

Type E

South Africa

In South Africa, outlets of type C, M and N are in use.

Type C

Type M

Type N